Among air-conditioning apparatuses, such as multi-air-conditioning apparatuses for buildings, the following type of air-conditioning apparatus is known. By circulating a refrigerant from an outdoor unit to a relaying unit and by circulating a heat medium, such as water, from the relaying unit to an indoor unit, transfer power of a heat medium, such as water, is reduced while circulating the heat medium in the indoor unit (for example, see Patent Literature 1).
The following type of air-conditioning apparatus is also known. A zeotropic refrigerant mixture is used, and a high-pressure side and a low-pressure side are connected to each other with a bypass pipe via a second decompressing device. The circulating composition of the zeotropic refrigerant mixture is calculated from a pressure signal and a temperature signal (for example, see Patent Literature 2).
A multi-air-conditioning apparatus that detects the composition of a zeotropic refrigerant mixture is also available (for example, see Patent Literature 3).